Induction system duct with noise attenuating holes

ABSTRACT

A duct for an induction system is provided that has an effective length between an inlet and outlet. An aperture is provided a wall of the duct at a location corresponding to a pipe resonance for attenuating noise at the pipe resonance frequency. In one example, the aperture is provided using a cluster of holes arranged at the location. Multiple apertures are arranged about a circumference of the duct, for example, at opposing sides of the duct. In one example, an aperture is provided at a distance of approximately one quarter the effective length from both the inlet and the outlet. A porous non-woven structure is arranged over the aperture to minimize pressure losses associated with the aperture.

BACKGROUND

This application relates to an induction system duct that incorporates noise attenuation features.

Typically, vehicle engine induction systems utilize several noise attenuation devices to attenuate undesired resonances within the induction system. It is sometimes difficult to incorporate the noise attenuation devices into an induction system due to limited packaging space, cost and complexity.

An induction system typically includes a duct having a pipe resonance associated with its effective length. Often these resonances are undesirable from an overall noise level and sound quality perspective. Typically, a Helmholtz resonator is added to the duct and tuned such that the undesired standing wave within the duct is attenuated. In particular, the volume of the “bottle” and size of the “neck” of the Helmholtz resonator is sized to attenuate a particular frequency in the induction system.

Packaging the Helmholtz resonator within the engine compartment can be difficult. Furthermore, the Helmholtz resonator is typically sized for the particular engine application. As a result, a greater number of parts are needed for a vehicle due to the variety of engines typically made available for vehicles.

What is needed is a noise attenuation device for a duct that is easy to package and that is versatile so that it may be used for different engines.

SUMMARY

A duct for an induction system is provided that has an effective length between an inlet and outlet. An aperture is provided a wall of the duct at a location corresponding to a pipe resonance for attenuating noise at the pipe resonance frequency. In one example, the aperture is provided using a cluster of holes arranged at the location. Multiple apertures are arranged about a circumference of the duct, for example, at opposing sides of the duct. In one example, an aperture is provided at a distance of approximately one quarter the effective length from both the inlet and the outlet. A porous non-woven structure is arranged over the aperture to minimize pressure losses associated with the aperture.

Accordingly, the example duct with noise attenuating apertures requires no significant additional packaging space and may be modified to suit a particular engine application.

These and other features of the application can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an example induction system.

FIG. 2A is a schematic view of an example duct configured to attenuate a first pipe resonance.

FIG. 2B is another example duct configured to attenuate a second pipe resonance.

FIG. 3A is a perspective view of an example duct.

FIG. 3B is another perspective view of the example duct shown in FIG. 3A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An induction system 10 is schematically shown in FIG. 1. The induction system 10 includes an air source 12 that provides ambient air to an inlet 18 of a duct 16. The duct 16 includes an outlet 20 that communicates with an engine 14. The duct 16 includes a wall 24 that provides a passage 22 extending between the inlet 18 and outlet 20.

In one example embodiment, the wall 24 of the duct 16 includes an aperture 26 arranged at a location 28 corresponding to a standing wave producing undesired noise. The aperture 26 permits air to flow between the outside environment and the passage 22 to attenuate the noise associated with the standing wave. In one example, a porous non-woven structure, such as an open-cell foam 30, overlaps the aperture 26 to minimize pressure losses attributable to the aperture 26.

Referring to FIGS. 2A and 2B, the duct 16 includes an effective length L. As shown in FIG. 2A, the duct 16 includes a first pipe resonance W1 within the passage 22. Apertures 26 a, 26 b are provided in the duct 16 at locations at a distance approximately one quarter the effective length L from the inlet 18 and outlet 20. In this manner, the frequency of noise associated with the first pipe resonance W1 is attenuated.

In the example shown in FIG. 2B, a second pipe resonance W2 is shown within the passage 22. The aperture 26 is provided at a location corresponding to a distance of approximately one half the effective length L. As a result, the noise frequency associated with the second pipe resonance W2 is attenuated. It should be understood, that a given duct 16 can incorporate multiple apertures to attenuate multiple pipe resonances.

Referring to FIGS. 3A and 3B, an example duct 16 is shown including mounting features 32, 34 for securing the duct 16 to support structure 36, for example, within the engine compartment. In the example shown, the noise attenuating apertures 26 a, 26 b are each provided by a pair of clusters of holes 38. The holes within a cluster are located in close proximity to one another. The number of holes and their size are designed to provide a desired area capable of attaining sufficient noise attenuation of the undesired pipe resonance. The area can be determined by modeling or empirically. The holes associated with providing an aperture can be located about a circumference of the duct 16 at the location 28. In the example shown, clusters of holes 38 are provided on opposing sides 40, which reduces the manufacturing costs associated with the duct 16 by enabling the cluster of holes 38 to be formed simultaneously from opposing sides.

In the example shown in FIGS. 3A and 3B, the porous non-woven structure is secured to an outer surface 44 of the duct 16 using an adhesive 46. The porous non-woven structure is open-cell foam 42, in one example. It may be desirable to provide the adhesive 46 adjacent to but not significantly overlapping the cluster of holes 38 to prevent blocking flow through the aperture. The foam 42 acts as a flow straightener as air surrounding the duct 16 enters the passage 22. As a result, pressure losses attributable to the aperture 26 are minimized.

In the example shown, the duct 16 is provided by securing first and second portions 48, 50 to one another at complimentary flanges 52. In one example, the duct 16 is constructed from plastic and secured, for example, by adhesive or welding. A seal 54 is provided on the first portion 48 at the outlet 20 to provide a seal between the duct 16 and an intake manifold, for example.

Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content. 

1. A duct for an induction system comprising: a wall providing a passage and having an effective length extending between an inlet and an outlet, the wall including an aperture at a location corresponding to an undesired pipe resonance, the passage in fluid communication with an outside environment through the aperture.
 2. The duct according to claim 1, comprising a porous non-woven structure overlapping the aperture.
 3. The duct according to claim 2, wherein the porous non-woven structure is foam.
 4. The duct according to claim 2, wherein the porous non-woven structure is arranged inside the pipe.
 5. The duct according to claim 2, wherein the porous non-woven structure is adhered to an exterior surface of the wall.
 6. The duct according to claim 2, wherein an adhesive is used to adhere the porous non-woven structure to the wall, the adhesive arranged adjacent to the aperture without significantly overlapping the aperture.
 7. The duct according to claim 1, wherein the aperture is provided by a cluster of holes in close proximity to one another.
 8. The duct according to claim 1, wherein the aperture is provided by multiple holes arranged about a circumference of the duct, the circumference at the location.
 9. The duct according to claim 8, wherein the holes are arranged on opposing sides to one another at the circumference.
 10. The duct according to claim 1, wherein multiple apertures are arranged along the effective length and configured to attenuate multiple undesired pipe resonances.
 11. The duct according to claim 1, wherein the location corresponds to a distance approximately one quarter the effective length from each of the inlet and outlet.
 12. The duct according to claim 1, wherein the location corresponds to a distance of approximately one half the effective length.
 13. The duct according to claim 1, wherein the aperture includes an area corresponding to a desired level of noise attenuation relating to the undesired pipe resonance.
 14. The duct according to claim 1, wherein the duct comprises first and second portions secured to one another to provide the passage. 